package com.atguigu.day09;

import com.atguigu.bean.WaterSensor;
import org.apache.flink.api.common.functions.MapFunction;
import org.apache.flink.api.java.tuple.Tuple1;
import org.apache.flink.streaming.api.datastream.SingleOutputStreamOperator;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.table.api.Table;
import org.apache.flink.table.api.bridge.java.StreamTableEnvironment;
import org.apache.flink.table.functions.AggregateFunction;
import org.apache.flink.table.functions.TableFunction;

import static org.apache.flink.table.api.Expressions.$;
import static org.apache.flink.table.api.Expressions.call;

public class Flink05_UDF_AggFun {
    public static void main(String[] args) {
        //1.获取流的执行环境
        StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();

        env.setParallelism(1);

        //2.从端口读取数据并转为WaterSensor
        SingleOutputStreamOperator<WaterSensor> waterSensorStream = env.socketTextStream("localhost", 9999)
                .map(new MapFunction<String, WaterSensor>() {
                    @Override
                    public WaterSensor map(String value) throws Exception {
                        String[] split = value.split(",");
                        return new WaterSensor(split[0], Long.parseLong(split[1]), Integer.parseInt(split[2]));
                    }
                });

        //3.获取表的执行环境
        StreamTableEnvironment tableEnv = StreamTableEnvironment.create(env);

        Table table = tableEnv.fromDataStream(waterSensorStream);

        //TODO 4.使用自定义函数查询数据

        //不注册直接使用
  /*      table.
                groupBy($("id"))
                .select($("id"),call(MyUDAF.class, $("vc")))
                .execute()
                .print();*/

        //先注册再使用
        tableEnv.createTemporarySystemFunction("avgVc", MyUDAF.class);

         /*table.
                groupBy($("id"))
                .select($("id"),call("avgVc", $("vc")))
                .execute()
                .print();*/


        tableEnv.executeSql("select " +
                " id," +
                " avgVc(vc)" +
                " from " +table+
                " group by id" +
                "").print();

    }

    //自定义一个聚合函数，求VC平均值
    public static class MyAcc{
        public Integer sum;
        public Integer count;
    }

    public static class MyUDAF extends AggregateFunction<Double,MyAcc>{

        //初始化累加器
        @Override
        public MyAcc createAccumulator() {
            MyAcc myAcc = new MyAcc();
            myAcc.sum = 0;
            myAcc.count = 0;
            return myAcc;
        }

        //累加操作
        public void accumulate(MyAcc acc, Integer value) {
            acc.sum += value;
            acc.count++;
        }

        @Override
        public Double getValue(MyAcc accumulator) {
            if (accumulator.count==0){
                return null;
            }else {
                return accumulator.sum*1D/accumulator.count;
            }
        }
    }

}
